Single crystal nickel-based superalloy casting compositions have been developed for their excellent high-temperature creep strength properties as required for the casting of high performance jet engine components such as turbine blades and/or for the fabrication of other metallic components which require high strength properties during prolonged and/or repeated use at very high temperatures. Reference is made to U.S. Pat. Nos. 4,885,216 and 4,677,035 for their disclosure of such single crystal nickel base superalloys.
While such single crystal superalloys represent a substantial improvement over prior known nickel base superalloys with respect to creep strength properties at high temperatures, they represent a compromise with respect to environmental attack during use, particularly due to hot corrosion caused by oxidation and/or sulfidation. Also, while such single crystal superalloy cast components such as turbine blades or shrouds have excellent high temperature strength they nevertheless are susceptible to erosion, rub damage, cracking and other damage during use, so as to require repair periodically, such as filling of cracks or surface wounds and build up or restoration of blade edges or blade tips.